Field devices, which serve for registering and/or influencing process variables, are often applied in automation technology. Examples of such field devices are fill level measuring devices, mass flow measuring devices, pressure and temperature measuring devices, etc., which, as sensors, register the corresponding process variables, fill level, flow, pressure, or, respectively, temperature.
Field devices such as, for example, actuators, serve for influencing process variables. Thus, actuators in the form of e.g., valves influence the flow of a liquid in a pipeline section or, in the form of pumps influence the fill level in a container. A large number of such field devices are available from the firm, Endress+Hauser.
As a rule, field devices in modern manufacturing plants are connected to superordinated units (e.g. control systems, control units, etc.) via fieldbus systems (HART, Profibus, Foundation Fieldbus, etc.). These superordinated units serve, among other things, for process control, process visualizing, process monitoring as well as for startup and servicing of the field devices.
A number of fieldbus systems can be used in such a plant. The fieldbus systems installed can also be, in such case, of different types. The plant can, for example, have a cell (which corresponds to a section in the plant), in which communications are conducted by means of the Profibus protocol via one fieldbus system, and can exchange process relevant information in another cell by means of the Foundation Fieldbus protocol via another fieldbus system. A plant with a number of fieldbus systems of different types is described, e.g., in Offenlegungsschrift (laid-open German application) DE 10049049 A1. There, a process control network is connected to a number of fieldbus systems via a central control unit and via interfaces, which are, in each case, independent of one another.
Different requirements are placed on fieldbus systems by the user; on the one hand, process control and, on the other hand, plant monitoring, or plant visualizing. In such a plant, the totality of devices, which serve for process control or for plant monitoring and plant visualizing, and their arrangement is referred to as a process control arrangement. Process control, in such case, is performed by the plant operator via a process control system.
For plant monitoring, it can be required, for safety reasons, to provide an access to the fieldbus system, which access is separate from the process control system. Fieldbus interfaces having this functionality have already become known from the state of the art. For example, fieldbus systems are integrated in enterprise networks, which work based on Ethernet. By means of the fieldbus interfaces, process or field device data can thus be accessed from different areas of an enterprise. For worldwide communication, the enterprise networks can also be connected to public networks, e.g. the Internet.
For servicing the field devices, corresponding operating programs are necessary. These operating programs can run, for example, on a computer, which is integrated in a superordinated communication plane. An example is the FieldCare product of Endress+Hauser. The operating programs have different functionalities as regards plant monitoring (the so called asset management).
The accessing of the fieldbus from a superordinated communication plane such as, for example, a company network, to a fieldbus has so far been associated with a high cabling effort as well as with complicated data addressing. Currently, each fieldbus interface must be individually connected to the superordinated bus system by cable in order to connect the fieldbuses to the superordinated bus system. If a number of fieldbus interfaces are used in a plant, then each of these devices, in each case, must be assigned an individual address, for example, an IP address, in the superordinated communication plane. Additionally, plant information is not centrally queryable, but is distributed on the memory units of the respective fieldbus interfaces of the plant and is separately queryable from there.
Moreover, one type of fieldbus interface covers, for example, in each case, only one fieldbus type. Moreover, the devices must be individually configured as well as parametered and updated.